The objective of the proposal is to determine what benefits estrogen replacement would have on cardiovascular risk factors, lipoprotein oxidation, glycemic control, and postprandial triglyceride concentrations in women with type II diabetes mellitus. Fifty postmenopausal women with type II diabetes will be treated with conjugated equine estrogen 0.625 mg/d and a placebo in a randomized crossover design, each for a duration of 8 weeks. At the end of the placebo and estrogen phases, duplicate lipoprotein profiles, apolipoproteins A-I and B, lipoprotein (a), fasting glucose, and glycosylated hemoglobin concentrations will be obtained. Lipoprotein fractions (VLDL, LDL, and HDL) will be isolated by sequential ultracentrifugation, then analyzed for lipoprotein oxidation, and the susceptibility of lipoprotein to further oxidation. The effect of estrogen on postprandial triglyceridemia will be tested by quantifying the plasma triglyceride excursion after a liquid fatty meal.